Recent sliding systems with onboard linear motor are finding extensively increased applications in various machines including semiconductor industries, various assembling machines, precise measuring/inspection equipments, testing machines, machine tools, and so on. The sliding systems are needed to be shrinking in size, compact and simple in construction, and yet having high propulsion, superior accuracy, high durability, high reliability, convenience to operate, less consumption of power and inexpensive cost in production. Moreover, the linear motion guide units having mounted with the sliding system constructed as stated earlier require maintenance-free for lubrication. To cope with the design considerations as stated earlier, there has been developed various sorts of sliding systems with onboard linear motor. Nevertheless, advanced machines are looking for the improved sliding system with onboard linear motor which, even though more shrinkage in construction, allows the slider moving over a longer stroke than ever with even more shrinkage in size, and finds more applications in extensive fields as well as more conveniences for usage.
An example of the sliding system with onboard moving-magnet linear motor is disclosed in, for example Japanese Laid-Open Patent Application No. 2007-300 759 which is a commonly-assigned senior application. This prior sliding system includes an elongated flat bed, a flat table overlying above the bed so as to move back and forth through linear motion guide units in a reciprocating manner along a direction longitudinally of the bed, a field magnet lying on the table in opposition to the bed, the field magnet being composed of magnet segments lying in a way unlike magnetic poles are juxtaposed alternately in polarity in a traveling direction of the table, and an armature assembly lying on the bed in opposition to the field magnet, the armature assembly being composed of coreless armature windings of flat rectangle in shape, which are arranged in juxtaposition in a direction longitudinally of the bed. With the prior sliding system constructed as recited earlier, the bed is made of magnetic material so as to serve as a winding yoke for magnetic circuit, while table is also made of magnetic material to serve as a magnet yoke for magnetic circuit. The armature assembly is made up of any number of armature windings lying in juxtaposition on an upper surface of elongated flat plate mounted on the bed, the armature windings being packaged with any adhesive molding applied around the armature windings. The prior sliding system was then expected of longer traveling stroke of the slider than ever, with high velocity running and high response, and shrinkage in construction.
To envisage the sliding system in which the stroke of the slider is even longer, it would be anticipated to extend lengthwise the table installed thereon with a linear scale or alternatively install the linear scale on the bed while elongate bed in length. For example, when the latter alternative is selected, the armature windings are arranged across the overall length of the bed. Every other armature windings but the ones opposing against the field magnet on the table would be energized at all times. This involves additional electricity and entails generation of much heat. Thus, it will be understood that either of the alternatives would have a limitation in potential stroke length of the slider.
Moreover, an example of the sliding system with onboard moving-coil linear motor is disclosed in, for example Japanese Laid-Open Patent Application No. 2001-25 229 which is also a commonly-assigned senior application. This prior sliding system is comprised of a linear motion guide unit having a guide rail of U-shape in transverse section, which has high rigidity enough to function as structural member, and a slider that fits into a U-shape recess inside the guide rail for sliding movement relatively to the guide rail, and a moving-coil linear motor actuating the slider to travel with reference to the guide rail. The moving-coil linear motor has a pair of field magnets installed on a magnet yoke lying on an outward surface of any one of widthwise opposing sides of the guide rail, and a moving-coil assembly secured to the slider in a way lying between the paired field magnets. The magnet yoke has a U-shape configuration in transverse section, which is defined with lengthwise sections opposite to one another and connected with each other along their bottom lengthwise edges. The magnet yoke is attached on the selected side of the guide rail in an orientation getting the U-shape opened upwards. The moving-coil assembly is fastened to a sidewise extension of a mounting base secured to the top of the slider, which is raised above the sides of the guide rail. With the moving-coil assembly, the armature windings are each made up of turns wound around a core of resinous molding, which fits to a coil board in a complementary mating manner to set securely in place the armature assembly relatively to the coil board.
The prior sliding system constructed as stated just earlier, however, wouldn't avoid getting too high or bulky in transverse section to more shrink in size. Industry is eager for the sliding system less in height than ever so as to make it possible to incorporate with miniature machines.